The prevalence of overweight/obesity among children and adolescents remains a public health priority. Interventions to treat children and adolescents currently struggling with excess weight are critical for prevention of obesity into adulthood. There is increasing evidence to support the efficacy of comprehensive lifestyle interventions for adolescents. Despite the emergence of such treatments, few adolescents benefit because these interventions are available primarily through carefully controlled clinical trials or delivered in specialized/tertiary clinical settings affiliated with academic medical centers. In 2010, the U.S. Preventive Services Task Force (USPSTF) provided a Grade recommendation B (i.e. the service is recommended with moderate/high certainty of benefit) for clinicians to screen children ages 6-17 years for obesity and refer identified youth to comprehensive behavioral programs. The challenge in meeting this objective is the lack of community-based obesity treatments to which to refer, particularly for adolescents. The JOIN program, developed as a collaboration between United HealthGroup and Y-USA is a pediatric weight control intervention targeted toward a broad age range of youth from 6-17 years that is: 1) based on well established and evidence based principles; 2) delivered by YMCA facilitators within a community setting: and 3) potentially scalable nationally. Findings from a 6-month pilot study examining the effectiveness of JOIN demonstrated impressive changes in weight status for school age children, but more modest results for adolescents. The goal of the proposed study is to modify the JOIN program to increase its effectiveness with adolescents while retaining its potential for scalability A tota of {120} adolescents (ages 13-17) with BMI > 85th% and < {50} will be randomly assigned to a 16-week enhanced JOIN program (TEEN JOIN), or the traditional JOIN intervention, followed by 6 monthly maintenance sessions. Evaluation of adolescent height, weight, group cohesion, objective physical activity, {dietary intake} and psychosocial outcomes will be obtained at baseline, 4 months, and 10 months. Additional outcomes will include treatment feasibility, including attendance, completion of diet and physical activity monitoring logs, and exit interviews with adolescents and parents regarding the intervention. We will also obtain preliminary indicators of cost effectiveness. It is hypothesized that adolescents who are randomized to TEEN JOIN will demonstrate greater decrease in BMI at 4 and 10 months than those randomized to JOIN. It is further hypothesized that adolescents randomized to TEEN JOIN will demonstrate greater increases in participation in moderate-vigorous physical activity and greater improvements in self-concept, self-efficacy related to physical activity, and group cohesion than adolescents who receive the standard JOIN condition. The next objective in this line of research is to conduct a large scale dissemination trial (R18) to evaluate the effectiveness of TEEN JOIN for adolescent weight control.